xxii 
Report on Salmon Fisheries. 
the Hockin fish- way is, in a great degree, exempt from these 
objections. 
Many forms of fish- way have been devised to facilitate the 
ascent of running-fish, such as Mr Call's lock swimming pass in 
England, Colonel Macdonald and Mr Bracketb's fish-ways in the 
United States of America, and the fish- way of MrEogers in Canada; 
all of which are clever and ingenious, and have been successfully 
applied in various parts of Europe and America. But, on the 
whole, the recent invention of Mr Hockin seems, in some respects, 
superior to any of them. One special advantage of it is, the position 
of the orifice through which it is supplied with water. The supply 
can never fail so long as there is water in the dam — and this is a great 
point — as the orifice is far below the level of the water in the dam. 
Whether the orifice will not be liable to be choked up with the 
gravel, which is brought down in floods, by some of our rapid 
Highland rivers, is a point more difficult to determine. Most of 
the fish-ways in Scotland are supplied with water through a cut 
made in the crest of the dam ; so that, whenever the water falls 
below the crest, the supply ceases, and the pass is useless. 
The following description by its inventor, and the drawings which 
illustrate and succeed it, will give a good idea of the peculiarities 
and advantages of the Hockin fish-way : — ' Deciding that the 
\ great defect of fish-ways in use was from the fact of their being 
' fed from the surface, and that it would be of great value if one 
' could be obtained that was fed from beneath, I instituted a series 
' of experiments last winter with this object in view, and succeeded 
* in inventing a pass which is a simple solution of the difficulty. 
' It may shortly be described as a hole in the bottom of the dam, 
' with the velocity of the discharge so reduced that a fish may con- 
' tend against the current, and swim into the pond above. It con- 
' sists of a series of compartments, having approximately a level 
' floor, with side walls, ends, and transverse partitions (every 4 feet of 
' its length) from the bottom of the dam to above the water line ; 
' these compartments connected with one another, and with the pond 
' above and the river below the dam, by submerged apertures 
' approximately on the level aud preferably in alignment for the 
* passage of fish. The water in the several compartments will be 
■ lower, step by step, from inflow to outlet, and will flow out of the 
' last aperture under a head of about 2 feet (it can be made less), 
' and, therefore, with so little velocity that fish can swim into the 
1 first compartment and into the pond above. Here, then, is a fish- 
' way which is not of very great length, 28 or 32 feet, sufficient 
' for any average dam. It is built from the bottom of the pond 
* up, so that ice cannot form under it nor raise it ; and from its 
* structure, with partitions every 4 feet, it is necessarily strong and 
' compact. Freshets can make no torrent through these passes 
' and tear them out. The apertureB being submerged cannot be 
* choked with debris, and they can be so far removed from the 
' bottom as to obviate any danger from that source. What is per- 
* haps most important is, that it adapts itself to the height of water 
' in the dam ; for, so long as there is water in the dam, the fish-way 
* will be supplied. The importance of this will be recognised when 
* it is remembered that a fish-way has no friend in the mill-owner, 
